A dot-immunobinding assay (DIA) for detection of viral antibody as well as antigens has recently been described (1-7). The simplicity of the procedure, which is also rapid, specific, sensitive, and inexpensive, lends itself to commercialization as a kit for use in an unsophisticated laboratory or in the field. No equipment other than that provided in the kit is needed. In Phase I, an SIV kit will be prepared as this virus has already been shown to be adaptable to the DIA (see references 1,2,5). In Phase II, various parameters expanding the original studies will be examined in order to ascertain the full potential of this projected kit. Essentially, what antigens (principally viral) are satisfactory for detection of antibody and what conditions are necessary to detect antigen in specimens will be determined. The DIA now consist of dotting relatively crude known antigens on nitrocellulose (NC) sheets to which serum or blood is added by means of filter paper. After a period of absorption, the sheets are washed, treated with immunoglobulin-conjugate and then subjected to a substrate-dye which stains the antigen-antibody complex. The converse, i.e., unknown antigen, is placed on NC sheets and known antiserum is used to identify an antigen. The entire procedure takes approximately 3-5 hr.